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 A123546 Triangle read by rows: T(n,k) = number of unlabeled graphs on n nodes with degree >= 3 at each node (n >= 1, 0 <= k <= n(n-1)/2). 3
 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 4, 5, 4, 2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 18, 30, 34, 29, 17, 9, 5, 2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 6, 35, 136, 309, 465, 505, 438, 310, 188, 103, 52, 23 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,36 REFERENCES R. W. Robinson, Numerical implementation of graph counting algorithms, AGRC Grant, Math. Dept., Univ. Newcastle, Australia, 1978. LINKS R. W. Robinson, Rows 0 through 14, flattened EXAMPLE Triangle begins: n = 0 k = 0 : 0 ************************* total (n = 0) = 0 n = 1 k = 0 : 0 ************************* total (n = 1) = 0 n = 2 k = 0 : 0 k = 1 : 0 ************************* total (n = 2) = 0 n = 3 k = 0 : 0 k = 1 : 0 k = 2 : 0 k = 3 : 0 ************************* total (n = 3) = 0 n = 4 k = 0 : 0 k = 1 : 0 k = 2 : 0 k = 3 : 0 k = 4 : 0 k = 5 : 0 k = 6 : 1 ************************* total (n = 4) = 1 n = 5 k = 0 : 0 k = 1 : 0 k = 2 : 0 k = 3 : 0 k = 4 : 0 k = 5 : 0 k = 6 : 0 k = 7 : 0 k = 8 : 1 k = 9 : 1 k = 10 : 1 ************************* total (n = 5) = 3 CROSSREFS Row sums give A007111. Cf. A007112, A123545. Sequence in context: A230564 A011174 A123545 * A339069 A334422 A317499 Adjacent sequences:  A123543 A123544 A123545 * A123547 A123548 A123549 KEYWORD nonn,tabf AUTHOR N. J. A. Sloane, Nov 14 2006 STATUS approved

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Last modified January 19 12:53 EST 2021. Contains 340269 sequences. (Running on oeis4.)